NE IX AND NE X SPECTRA ON THE JET TOKAMAK

Observations of H-like Ne X and He-like Ne IX soft x-ray emission line spectra have been made on the JET (Joint European Torus) tokamak. Rec ently calculated electron impact excitation rates for He-like neon are used in the derivation of the electron temperature sensitive line rat ios G = [(x+y+z)/w], R1 = (1s3p P-1(1) --> 1s2 1s0)/omega Ly(alpha)/om ega, and the electron density sensitive ratio R = [z/(x+y)], where w, x, y and z are the resonance line (1s2p P-1(1) is S-1(0) intercombinat ion (1s2p P-3(2.1) --> 1s2 S-1(0) and forbidden lines (1s2s S-3(-1) -- > 1s2 S-1(0)) respectively and Ly(alpha) is the H-like Lyman(alpha) tr ansition. Extensive modelling is carried out to allow for non-coronal conditions due to diffusion effects in these calculations, which are c ompared with experimental ratios from JET, where independent temperatu re and density measurements are available. Departures from equilibrium are found for both ohmic and additionally heated plasmas, resulting i n significant changes to the G and Ly(alpha) ratios. The R ratio is ap proaching its upper density limit and is relatively unaffected by non- coronal conditions. Good agreement between the experimental and calcul ated ratios is found, giving an indication of the accuracy of the comb ination of the atomic data and transport employed in the calculations.